The present invention relates to a device for sensing medicament dosing in a drug infusion set. In some embodiments it also includes the ability to retain and recall dosing history and to provide tactile feedback to a user reflecting recent dosing activity. In some embodiments it also includes the ability to retain and dosing history and to provide a download of that history to an electronic device such as a computer or a similar device specifically for that purpose.
The invention relates to a sensing device that is applicable to infusion devices for liquid medicaments in general, but for purposes of example, the use of the device in connection with disposable infusion devices for the administration of insulin in diabetes is described below.
Glucose is the central source of energy in the human body, and is generated by the digestion of the food, particularly carbohydrates and released into the bloodstream for distribution throughout the body. Insulin is a hormone that allows the glucose in the bloodstream to be absorbed by the cells of the body. A healthy person makes enough insulin for the body's cells to absorb essentially all the glucose generated by the food that the body digests. Insulin is produced in the pancreas and released into the bloodstream and is present at a low basal level at all times, but is sometimes released in larger bolus amounts in response to or anticipation of a person's intake of carbohydrates, for example at a meal.
Diabetes is a disorder of the manufacture and utilization of insulin. It is a huge and growing health problem among virtually all segments of the population. It is an incurable and progressive disease that typically manifests itself in one of two different ways, type 1 diabetes (T1) and type 2 diabetes (T2). In T1 diabetes the patient loses the ability to make insulin at all, generally as a result of destruction of cells of the pancreas. This often happens early in life and was previously sometimes called early onset diabetes. With this type of diabetes, insulin replacement therapy is necessary, and without the administration of insulin the patient dies.
In T2 diabetes, the patient develops an inability to use insulin efficiently. Often diet and exercise will delay progression, but the disease typically progresses to the stage where it is necessary to administer drugs to increase the body's production of insulin or the efficiency of use of the insulin present. At some point thereafter, the disease usually progresses to the point that insulin injections are required.
In both T1 and T2 where insulin injections are required, careful monitoring of the amount and timing of injections is important. Certain insulin analogs have been developed that allow a single or perhaps two daily injections to provide the rough equivalent of the daily basal insulin of a patient without diabetes. However, mimicking the body's bolus insulin amounts is far more delicate. Bolus administrations of insulin are typically given about half an hour before a meal. The amount of insulin that is appropriate varies from one administration to the next depending on the amount and type of the food to be eaten, the amount of exercise that the patient has recently engaged in, the how tired the patient is, and any number of other factors.
Recent treatment protocols are trending toward a move to earlier treatment of T2 diabetes with insulin, and in more precise and constant monitoring of the blood glucose level of the patient. This protocol is sometimes referred to as Intense Insulin Therapy, or IIT and involves the administration of insulin three or more times per day, or constant administration by a pump. As a result, in addition to the growing problem of diabetes in the population, it is likely that in the future a larger portion of people with diabetes will be treated by the administration of insulin, and IIT will become far more common.
Administration of insulin has traditionally been accomplished using a syringe. Recently, needle carrying pen-like devices have also been employed for this purpose. Both forms of insulin administration require the patients to stick themselves each time they inject insulin, often many times a day. Additionally, the act of injecting themselves or having a helper inject them is socially awkward for the person with diabetes. Thus, these traditional forms of insulin administration have been a rather pervasive intrusion in the lives and routines of the patient's who have had to adopt and employ them. If the social awkwardness results in a patient skipping administrations, that may be detrimental to control of the disease.
More recently, insulin pumps attached by tubing to an infusion set mounted on the patient's skin have been developed as an alternative form of insulin administration. Such pumps may be controlled by a programmable remote electronic system employing short range radio communication between a control device and electronics that control the pump. While such devices may involve fewer needle sticks, they are expensive to manufacture, complex to operate and cumbersome and awkward to wear. Further, the cost of such devices can be many times the daily expense of using a traditional injection means such as a syringe or an insulin pen.
Devices of the type mentioned above also require a significant amount of training to control and use. Great care in programming the devices is required because the pumps generally carry sufficient insulin to last a few days and improper programming or operation of the pumps can result in delivery of an excessive amount of insulin which can be very dangerous and even fatal.
Many patients are also reluctant to wear a pump device because they too are generally socially awkward. The devices are generally quite noticeable and can be as large as a pager. Adding to their awkwardness is their attachment to the outside of the patients clothes and the need for a catheter like tubing set running from the device to an infusion set located on the patient's body. Besides being obvious and perhaps embarrassing, wearing such a device can also be a serious impediment to many activities such as swimming, bathing, athletic activities, and activities such as sun bathing where portions of the patient's body are necessarily uncovered.
In view of the above, a more cost effective and simple device has been proposed whereby an injection system is discreetly attached directly to the skin of the patient. The device may be attached to the patient under the patient's clothing to deliver insulin into the patient by the manual pumping of small doses of insulin out the distal end of a temporarily indwelling cannula that is made a part of the pump device. The cannula may be made a part of the drug delivery device before, during or after the attachment of the drug delivery device to the skin of the patient. The device may be made quite small and, when worn under the clothes, entirely unnoticeable in most social situations. It may still carry sufficient insulin to last a patient several days. It can be colored to blend naturally with the patient's skin color so as not to be noticeable when the patient's skin is exposed. As a result, insulin for several days may be carried by the patient discreetly, and conveniently applied in small dosages after only a single needle stick. For a more complete description of devices of this type, reference may be had to co-pending application Ser. No. 11/906,130, filed on Sep. 28, 2007 for DISPOSABLE INFUSION DEVICE WITH DUAL VALVE SYSTEM, which application is owned by the assignee of this application and hereby incorporated herein by reference in its entirety.
As noted above, current medical protocol is trending toward IIT where frequent and precise insulin administration is used. Also as noted above, each bolus insulin dosage is unique and will vary from one to the next. It is therefore very important to keep track of the timing and amount of each dosage. Patients are often advised to keep journals whereby they record each insulin administration and their blood glucose in frequent intervals to help carefully monitor their treatment.
Where the administration of the dose of insulin involves loading a syringe or dialing an amount on an insulin pen, and injecting oneself with the dose, the patient is unlikely to forget that they had administered the dose or the amount of the dose. Likewise if a complex electronic unit is controlling an insulin pump, one of its electronic functions can be to recall each dose and display the results on the individual remote unit. However, the very simple and discreet nature of the disposable unit described above makes it more likely that the patient may not remember the details of the last insulin administration. The fact that the device is worn on the patient's body in an unobtrusive manner also makes a visual display less useful. It is very likely that the patient will be wearing the device where they cannot easily see it. Finally, in furtherance of the goal of making the treatment less of an unpleasant intrusion into the daily life of the patient, it would be helpful to have a means of keeping a record of insulin treatment without the need to carry and maintain a journal.
Thus there is a need for a sensing device for use with an attached drug delivery device that can sense dosing by that device, and respond to a query from a user with information regarding recent dosing activity. There is a need for such a device that can provide that response in a tactile form that may be sensed by the user without the need to see the sensing device. There is a need for such a device to be discreet to be consistent with the ability of such a drug delivery device to be discreet and unobtrusive. Finally it would be useful if such a device could store the history of the insulin administration over a significant period of time and provide that information later to a physician or patient.
As mentioned previously, the administration of insulin is used here for exemplary purposes. However the administration of any liquid medicament, particularly where relatively frequent or constant administration is indicated, would be greatly aided by this invention. For example, where administration of pain medication for a chronic situation is required, an unobtrusive infusion device would be helpful, and a method of sensing and later providing information concerning recent dosing or long term dosing history would be very helpful. In some chemotherapeutic regimes, a similar system would be very useful. The invention is not limited by the exemplary method described herein except as explicitly stated in the claims.